Lightning Strike Damages to an MV Installation:
Diagnostics and Vulnerabilities Identification

François Grange | Sébastien Journet | Farid Paul Dawalibi | Alexandre Sellier | Yexu Li

Finding and understanding the exact course of a lightning incident on an electrical network is essential but can prove to be a particularly complex and challenging task. This paper presents an innovative global approach to diagnose and identify vulnerabilities of an electric distribution network including an overhead MV line and a substation under lightning stress. A new methodology based on lightning detection network data, field measurements and detailed simulations is proposed. IThe paper demonstrates that a realistic computer model that duplicates the distribution line its towers, grounding systems including the real soil characteristics are crucial to determine the origin of the substation damages and propose mitigation measures.

2023 International Symposium on Lightning Protection (XVII SIPDA)

Shielding Analysis of Enclosures Made of Arbitrary
Simple Material Using a Novel Combination of
Open Surface Integral Equations

Parisa Dehkhoda, Member, IEEE | Rouzbeh Moini, Senior Member, IEEE
Simon Fortin, Member, IEEE | Farid P. Dawalibi, Senior Member, IEEE

A new set of surface integral equations for computing the shielding effectiveness of an enclosure made of any simple (linear, homogeneous, and isotropic) material is presented and discussed. First, the assumption of a thin slab is used to ignore the equivalent currents on the side surfaces of the slab. Then, four equations are derived from the electric and magnetic field integral equations for the outside and inside regions of the slab. The total number of equations is then reduced to two independent equations by applying the approximate surface impedance relationships for a thin material slab. The established formulation is discretized through the method of moments by rooftop basis functions over flat quadrilaterals represented as bilinear surfaces, with razor-blade functions used for the testing procedure. It is shown that the electromagnetic response of a very thin material plate can be represented by the sum of the responses of a perturbed perfect electric conductor and a perturbed perfect magnetic conductor. The accuracy of the method is first evaluated for several frequencies and various types of materials, using available numerical methods and measurements. Then, a practical example of the magnetic shielding effectiveness of a rectangular enclosure made of a Mu-metal material is analyzed for frequencies up to 1 MHz.

Published in: IEEE Transactions on Electromagnetic Compatibility
( Volume: 65, Issue: 6, December 2023)

Lightning Overvoltage and Transient Ground
Potential Rise in Large PV Plants

François Grange | Sébastien Journet | Farid Paul Dawalibi | Zainal Kadir

Photovoltaic (PV) power plants cover large areas that are susceptible to multiple lightning strikes. Consequences of the electromagnetic interference caused by lightning can be a major concern for people safety and equipment integrity. In this paper, we investigate lightning overvoltage and transient ground potential rise in large PV plants for different lightning strike scenarios. The main objectives of this paper is to describe the analysis that was carried out and propose cost-effective mitigation techniques based on the most advanced simulation techniques.

2022 36th International Conference on Lightning Protection (ICLP)

Extended Earthing System Impedance Measurements:
Precautions and Solutions

F. Grange | S. Journet | A. Sellier | F. P. Dawalibi

An appropriate earthing system should reduce the effect of earth potential differences (voltages) between accessible points to levels that do not endanger people’s safety nor equipment integrity under normal and fault conditions. Thus, measurement campaigns are of particular importance to confirm that a specific design meets the desired safety targets. The French regulatory and international standards propose a qualitative method but does not provide a clear quantitative approach. Modern techniques for measuring the performance of an earthing network are commercially available but suffer from a lack of reliability. In this article, we present a measurement campaign performed in a complex environment whereby, the interpretation of Fall-of-Potential earth impedance tests is enhanced and complemented by simulating the same environment with appropriate software packages to confirm that the measured values are accurately selected and interpreted. This paper explores an actual field measurement case and describes the precautions and methodology used for measuring and interpreting the performance of an extended earthing network.

21^st International Symposium on High Voltage Engineering, Budapest, Hungary, August 26-30, 2019

Integrity of Earthing Systems: An Innovative Approach
to Improve the Test Procedure Accuracy

F. Grange | S. Journet | P. Dziwniel | F. P. Dawalibi

A properly designed, installed, and maintained earthing system is imperative for a safe and effective operating substation. The testing and evaluation of an earthing system to determine its current condition is the first step in a process to correct problems. In this article, a working methodology is established to carry out more accurate integrity tests thanks to an innovative approach. Here we present an innovative methodology for testing the integrity of the earthing network using a multi-step process. Hence, we rely on a dual approach integrating both measurements and simulations and use Enedis facilities at different stages of construction to establish action-triggering values. By performing a measurement campaign on a pilot site with only the well-known earthing network and no aerial parts, we have shown a good agreement between voltage drop measurement values and simulation results. Such results have been compared to a a preliminary integrity evaluation guideline based on simple theoretical approach considerations. The inaccuracy of a typical analytical criteria has been demonstrated and perspectives for this work are presented.

21^st International Symposium on High Voltage Engineering, Budapest, Hungary, August 26-30, 2019